Write the electronic configuration of the element with atomic number of `9, 11, 21` and `36`. Predict the folloiwng from these configurations:
(a) Which of them has the lowest ionisation potential ?
(b) Which of them has the highest electron gain enthalpy ?
( c) Which of them are non-metals?
(d) Which of them has zero electron gain enthalpy ?

Explanation

To solve the question, we will follow these steps:

### Step 1: Write the electronic configurations of the elements with atomic numbers 9, 11, 21, and 36.

1. **Atomic Number 9**: The electronic configuration is:
\[ 1s^2 \, 2s^2 \, 2p^5 \]
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